The present invention generally relates to linear lighting apparatuses. More specifically, the present invention describes an apparatus and method for increased lighting efficiency in a linear lighting apparatus with a plurality of optical assemblies.
Many linear lighting apparatuses exist in the lighting industry today. Several of these apparatuses use light-emitting diodes (“LEDs”) as light sources. LEDs are individual point light sources that each deliver a singular beam of light. When organized in a linear array, the individual beam patterns from each LED are very apparent, resulting in a “scalloping” effect. Eliminating this effect when grazing building facades or glass, for example, is highly desirable. Currently, the only light source that can deliver this continuous, uninterrupted beam of light is fluorescent light sources. However, LEDs are preferred as light sources over fluorescent lights as LEDs can produce a more concentrated beam of light at nadir while consuming less energy than fluorescent lights.
Current linear lighting apparatuses attempt to remedy the scalloping effect of LEDs light sources. However, these lighting apparatuses typically use very inefficient materials and designs for transmitting the light produced by the LEDs. For example, many of the current lighting apparatuses use reflective materials or a singular refractive material in order to direct the LED light from the apparatus.
The use of a reflective material is a very inefficient manner in which to harness and direct light emitted by LEDs. Specifically, the use of reflective materials is very difficult to control the direction of emitted light in very tight spaces. In addition, reflective materials lose a considerable amount of light emitted from the LEDs in trying to reflect the light in a given direction.
The use of refractory materials does provide a higher lighting efficiency than the use of reflective materials, but is far from optimized in current apparatuses and methods. Specifically, current lighting apparatuses employing a refractive material use a singular refractive optical assembly to direct light emitted by LEDs. The use of a singular refractive assembly does not optimize the amount of light harnessed by the assembly and emitted by the apparatus. For example, a substantial portion of light emitted by an LED may not enter into and be refracted by the single optical assembly. The light that does not enter into the optical assembly is therefore lost.
In addition, current linear lighting apparatuses provide a physical gap between an LED and a refractive optical assembly to allow for dissipation of the heat generated by the LED. However, this physical gap allows for a considerable amount of light emitted by the LED avoid being refracted by the optical assembly. Therefore, current linear lighting apparatuses are inefficient in their transmission of light from a light source to the atmosphere around the lighting apparatus.
Increased lighting efficiency is desired for linear lighting apparatuses due to their use in both indoor and outdoor applications. For example, current linear lighting apparatuses may be used to light a billboard or a facade of a building. Such an outdoor application requires considerable luminous flux from a lighting apparatus. In order to increase the amount of light (or luminous flux) output by an apparatus, the number of LEDs in the apparatus or the light-transmission efficiency of the apparatus must be increased. However, as described above, each LED produces a considerable amount of heat. Increasing the number of LEDs in an apparatus only adds to the amount of heat present in the apparatus. This increased heat can drastically shorten the lifespan of the lighting apparatus.
In addition, increased lighting efficiency is desired for linear lighting apparatuses due to their use in tight, or small architectural details. For example, many linear lighting apparatuses are placed along a narrow opening along a building facade. Due to space constraints, the lighting apparatuses must be small in size, or profile. However, as described above, the luminous flux output of the apparatuses must be considerable. Therefore, a need exists for a linear lighting apparatus that can fit in small locations and still produce considerable luminous flux. In order to meet this need the light efficiency of the linear lighting apparatus must be increased.
Therefore, a need exists to increase the light-transmission efficiency of a linear lighting apparatus without increasing the amount of heat generated. Such an apparatus preferably would provide for a significant increase in the light-transmission efficiency of a linear lighting apparatus without adding to the number of LEDs used to produce a given amount of light. By increasing the light-transmission efficiency of a linear lighting apparatus without adding to the number of LEDs, an improved linear lighting apparatus may produce an equivalent or greater amount of light as current linear lighting apparatuses without producing additional heat.